SCL Flight Software
Spacecraft Command Language (SCL) provides a scripting executive that allows priority-based parallel execution of scripts and rules for flight embedded systems. The SCL Real Time Engine (RTE) contains a rule-base Expert System and a command interpreter. The Expert System and command interpreter share the same code and behavior allowing the system to reduce the amount of code that must be verified and validated before flight.
The SCL system is designed to allow the same software architecture to be used for both flight and ground segments. Scripts developed and tested on the ground can be reused and moved directly onto the flight system with no loss of knowledge. The flight system allows closed loop control to be accomplished where ground contact is normally needed to make critical decisions. This paradigm shift reduces the need for ground personnel and lowers cost of ownership.
The SCL flight system can be integrated on top of a legacy system. The SCL flight software is designed to be reusable and has been fielded on many spacecraft missions, including:
Clementine - Launched January 25, 1994
FUSE - Launched June 24, 1999 - operated for 8 years
SCL also used in the ground station
Interim Control Module (ICM) - Developed late 1990s (Not Flown)
Received Man-Rating from NASA
EO-1/Autonomous Sciencecraft Experiment (ASE) - Operational on EO-1 since 2005
Co-Winner 2005 NASA Software Of The Year Award
TacSat-2 - Launched December 16, 2006
TacSat-3 - Launched May 19, 2009
TacSat-4 - Launched September 27, 2011
ORS Sat-1 - Launched June 29, 2011
SCL has been deployed in numerous simulators and testbed configurations in support of SCL and non-SCL spaceflight missions and other applications.
The SCL Flight software system includes:
SCL Real Time Engine
Rule Based Expert System
Scheduling Manager
Command Execution Manager
SCL shared memory database
SCL decommutation engine
SCL Packet Generator
Software Message Bus - Compatible with the Real-Time Operating System
SCL Compiler - workstation development environment
Developer/User Interface - workstation development environment
For information on the SCL Ground Software click here.